Sunday, 19 May 2024

Exclusion area around Mount Ibu, Halmahera Island, extended following new eruption.

The Indonesian Center for Volcanology and Geological Hazard Mitigation has extended the exclusion zone around  Mount Ibu, a 1325 m stratovolcano on the northwest coast of Halmahera Island, following a new eruption on 18 May 2024. A two kilometre exclusion zone had already been put in place after the volcano began erupting on 28 April, but this has been increased to seven kilometres following the most recent eruption, which produced an ash column which rose to 4 km above the volcano's summit, resulting in seven villages needing to be evacuated. 

An ash column and lava fountain above Mount Ibu on the Indonesian island of Halmahera on 18 May 2024. Several lightning discharges can be seen within the ash column; ash columns can build up considerable charge variations leading to frequent electrical discharges. Indonesian Center for Volcanology and Geological Hazard Mitigation/Reuters.

The Halmahera Island chain is a volcanic arc formed where the Halmahera Plate, a northeaster extension of the Molucca Sea Plate is being subducted beneath Philippine Plate from the east and the Eurasian Plate from the west, with the underlying plate being melted by the heat of the Earth's interior, and lighter minerals bubbling up through the overlying plate to form volcanoes. The Halmahera volcanoes are located where the Philippine Plate is overriding the Molucca Sea Plate; to the west the Sangihe Islands lie where the Molucca Sea Plate is being overridden by the Eurasian Plate.

Diagrammatic representation of the subduction zones beneath Halmahera (middle), plus the Philippines (top) and Sulawesi (bottom), with the Eurasian Plate to the left, the Molucca Sea Plate in the middle, and the Philippine Plate to the right.  Hall & Wilson (2000).

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